Air pollution measurement as a tool for practical policy and control strategy

Summary The problems of air pollution are discussed and possibilities for control and monitoring by analytical measurement are presented.

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Messung der Luftverschmutzung als Mittel für praktische Kontrollmanahmen

Zusammenfassung Die Problematik der Luftverschmutzung wird diskutiert und Möglichkeiten zur Kontrolle und Überwachung besprochen.

Lecture presented at Euroanalysis I Conference, 28. 8.–1. 9. 1972 in Heidelberg, Germany.     

Mutagenicity testing as an analytical tool in environmental pollution control

Screening of the environment for mutagens and carcinogens is a task which presents particular problems. Carcinogenicity tests involving mammals are prohibitively expensive for routine purposes and current procedures using the Salmonella reverse mutation test are insufficient.     

Kinetics of the enzymatic saccharification of pretreated tapioca waste (Manihot esculenta) and water hyacinth (Eichhornia crassipes)

Studies were carried out on saccharification of pretreated tapioca waste and water hyacinth under two different conditions: using microbial enzymes (cellulase fromMyrothecium verrucaria, Coprinus comatus,Pleurotus florida, andCellulomonas sp.) and solid-state fermentation. The rate of saccharification was determined at different temperatures, pH, substrate concentration, and incubation period. It was found that as the source of the enzyme varies, the optimal temperature and pH for the saccharification varies. Among the two different treatments, enzymatic saccharification was found to be the most efficient. Among the various cellulase sources tested, M.verrucaria cellulase was found to be the most efficient one followed byC. comatus, P. florida, and finallyCellulomonas sp.     

Virtual sensor array as a tool for classifying air pollution

This work examined the acquisition of information about gases using a virtual sensor array and classification. We were particularly interested in the approach in which classes are defined in a qualitative–quantitative manner, that is, by identifying the gas and concentration range. This type of information will be of interest for air pollution assessment purposes. In this field of application, it is often not necessary to provide very precise information. The idea of the virtual sensor array exploits the dependence of a gas sensor’s response on operating conditions. Originally it was developed as a means to improve the selectivity of an electronic nose when energy consumption by this device was a serious limitation. If the response of one sensor is measured in n time points, and each time point is characterised by different controlled exposure conditions, the sensor becomes analogous to an n-dimensional virtual sensor array. Compared with conventional approaches, a virtual sensor array based on a single sensor offers low power consumption, low volume, and low cost, which opens up new markets for wide application of portable and handheld devices. In this article, we show that a virtual sensor array and classification may serve as a reliable source of qualitative–quantitative information about gases. Twenty-six classes (five substances, each at five concentration ranges, and pure air) were recognised with a true positive rate higher than 99.14 ± 0.49% and a true negative rate higher than 99.21 ± 0.52%. As demonstrated, the basis for recognition could be a virtual sensor array associated with a low-power consuming sensor (210–280 mW). The complexity of the applied classifier could be adjusted depending on the choice of sensor operating conditions. For a complex classifier like support vector machine, dynamic exposure was sufficient to obtain high classification performance. A simpler classifier like k-nearest neighbours required more information, that is, information associated with static as well as dynamic exposure.     

New Phenylphenalene Derivatives from Water Hyacinth (Eichhornia crassipes)

Water hyacinth (Eichhornia crassipes) is a cause of great concern in terms of environmental and agricultural impacts in many parts of the world. Phytochemical investigation of water hyacinth led to the isolation of six new phenylphenalenes, 2,3‐dihydro‐3,9‐dihydroxy‐5‐methoxy‐4‐phenyl‐1H‐phenalen‐1‐one ( 1 ), 2,3‐dihydro‐8‐methoxy‐9‐phenyl‐1H‐phenalene‐1,4‐diol ( 2 ), 2,3‐dihydro‐4,8‐dimethoxy‐9‐phenyl‐1H‐phenalen‐1‐ol ( 3 ), 2,3‐dihydro‐9‐(4‐hydroxyphenyl)‐8‐methoxy‐1H‐phenalene‐1,4‐diol ( 4 ), 2,6‐dimethoxy‐9‐phenyl‐1H‐phenalen‐1‐one ( 5 ), and 7‐(4‐hydroxyphenyl)‐5,6‐dimethoxy‐1H‐phenalen‐1‐one ( 6 ), together with the four known compounds 7 – 10 . Their structures were elucidated by spectrometric methods including 1D‐ and 2D‐NMR, and MS analysis. These compounds may be involved in allelopathic interactions of water hyacinth with neighboring plants.     

Water hyacinth modified carbon paste electrode for simultaneous electrochemical stripping analysis of Cd (II) and Pb (II)

In this study, we demonstrated a highly sensitive electrochemical sensor for the simultaneous detection of Pb (II) and Cd (II) in aqueous solution using carbon paste electrode modified with Eichhornia crassipes powder by square wave anodic stripping voltammetry. The effect of modifier composition, pH, preconcentration time, reduction potential and time, and type of supporting electrolyte on the determination of metal ions were investigated. Pre-concentration on the modified surface was performed at open circuit. The modified electrode exhibited well-defined and separate stripping peaks for Pb (II) and Cd (II). Under optimum experimental conditions, a linear range for both metal ions was from 10 to 5000 μg L^?1 with the detection limits of 4.9 μg L^?1, 2.1 μg L^?1 for Cd(II) and Pb (II), respectively. The modified electrode was found to be sensitive and selective when applied to determine trace amounts of Cd (II) and Pb (II) in natural water samples.     

Atomic layer deposition (ALD) as a coating tool for reinforcing fibers

Layers of alumina were deposited on to bundled carbon fibers in an atomic layer deposition (ALD) process via sequential exposure to vapors of aluminium chloride and water, respectively. Scanning electron microscopic (SEM) images of the coated fibers revealed that each individual fiber within a bundle was coated evenly and separately, fibers are not bridged by the coating. SEM and transmission electron microscopic (TEM) images indicate that the coating was uniform and conformal with good adhesion to the fiber surface. Average deposition rate, measured from SEM images, was 0.06 nm per cycle at 500 °C. SEM also revealed that at deposition temperatures of 500 °C few of the fibers were damaged. At temperatures of 300 °C, no damaged fibers were observed, the average deposition rate decreased down to 0.033 nm per cycle. Oxidation resistance of the alumina-coated fibers was characterized by thermogravimetric analysis (TGA). The alumina coating improved oxidation resistance of the carbon fiber significantly. Oxidation onset temperature was 600 °C for fibers coated with a 45 nm thick alumina. Uncoated fibers, on the other hand, started to oxidize at temperatures as low as 250 °C.     

The use of radium isotopic ratio in groundwater as a tool for pollution source identificatioin

Radium isotopes were measured in groundwater near a radioactive storage facility with contained pasty residues from monazite and industrial processing sealed in concerete reserouirs. The concentration of radium isotopes in the water was slightly higher than found in the normal drinking water. The measured²²⁸Ra to²²⁵Ra ratio in the groundwater is not compatible with calculations of radium isotopes ingrow and docay in cake II for different elapsed times, leaving mesothorium cake as the most likely source of contamination.     

Response surface methodology (RSM) as a tool for optimization in analytical chemistry

A review about the application of response surface methodology (RSM) in the optimization of analytical methods is presented. The theoretical principles of RSM and steps for its application are described to introduce readers to this multivariate statistical technique. Symmetrical experimental designs (three-level factorial, Box-Behnken, central composite, and Doehlert designs) are compared in terms of characteristics and efficiency. Furthermore, recent references of their uses in analytical chemistry are presented. Multiple response optimization applying desirability functions in RSM and the use of artificial neural networks for modeling are also discussed.     

Schiff base copper(II) chelate as a tool for immobilization of protein

In our previous report a new methodology for intermolecular cross-linking or bridging of protein utilizing a spontaneous chelate formation process was proposed. In this paper the reliability of the process as a tool for protein immobilization has been further evaluated. The chromatographic behavior of tryptophan in a column packed with Sepharose coupled with salicylaldehyde residue showed that the alpha-amino acid was bound tightly to the gel in the presence of copper(II) ion and was eluted by the addition of ethylenediaminetetraacetate (EDTA). It was also proved that subtilisin modified with an alpha-amino acid residue was immobilized on the column, and this binding was reversed by the addition of EDTA as well.     

Ring-opening cross-metathesis (ROCM) as a novel tool for the ligation of peptides

The development of ring-opening cross-metathesis (ROCM) as a novel tool for the site-specific ligation of peptide units is reported. The resulting structural units at the site of ligation resulting from ROCM resemble proline as well as other known beta-turn stabilising structural units. ROCM under mild reaction conditions between a variety of peptides bearing a cyclic olefin with amino acids or peptides results in high yields. The peptidic cross-partners for metathesis are equipped with double bonds via the N and the C terminus and the side chain, respectively, to allow the synthesis of linear as well as non-linear and branched peptides. The ligation in this manner succeeds with low catalyst loadings, with no need for any excess of one reaction partner and with a high compatibility with a wide range of functional groups. Furthermore, the stereochemical outcome of the ROCM can easily be controlled by using a Hoveyda-type chiral catalyst. Fluorescence labelling of peptides is possible in the same manner when using a cyclic olefin equipped with a fluorescence marker.     

A weak acid extraction method as a tool for the metal pollution assessment in surface sediments

A simple technique has been evaluated for the initial assessment of heavy metal pollution in coastal sediments, in order to overcome many difficulties involved in routine monitoring of such analytes.The leaching of sediment samples with a cold dilute HC1, which affects only the non-residual part of the metals, gives the anthropogenic fingerprints on the bottom deposits and provides more data on the extent of heavy metal pollution relatively to the total sediment analysis.The proposed technique has been applied in most Hellenic coastal regions, both polluted and unpolluted. Comparisons between the various regions with the use of an enrichment factor have been made, which establish the gross degree to which a sediment population has been subjected to heavy metal pollution from the overlying waters.     

Analysis of western redcedar (Thuja plicata Donn) heartwood components by HPLC as a possible screening tool for trees with enhanced natural durability

A method is described for the quantitative analysis of seven known compounds, specifically plicatic acid, thujaplicatin methyl ether, beta-thujaplicin, gamma-thujaplicin, beta-thujaplicinol, thujic acid, and methyl thujate, in the ethanol extract of second growth western redcedar heartwood (Thuja plicata Donn) by high-performance liquid chromatography using diode array detection. The para bromo phenacyl ester of crotonic acid is synthesized for use as the internal standard for the method. Separation of compounds covering a wide range of polarities is achieved using an Inertsil ODS 3 3-micro column. Twenty seven second growth trees ranging in age from 40 to 125 years, originating from the coastal and interior regions of British Columbia, are selected for analysis and profiled using the described method. Samples consisting of five growth rings each are analyzed from the heartwood-sapwood boundary to the pith for each tree. Substantial variation in most heartwood compounds are detected within and between trees within a region. Significant variation in beta-thujaplicin, the ratio between gamma- and beta-thujaplicin, and methyl thujate is detected between coastal and interior populations.     

Generalized criterion of solvent polarity as a tool for control of chromatographic process

The generalized (reductive) criterion of solvent polarity was obtained by the method of multiparametric optimization of the Snyder index P", Hildebrand parameter _T , permittivity _r , and solvatochromism parameter E _T (30). Possibilities of employing this criterion for estimation of the elution power of normal and reversed mobile phases used in high-performance liquid chromatography were considered.     

Capillary zone electrophoresis as a tool for the quality control of goldenseal extracts

The root extracts of goldenseal (Hydrastis canadensis L.) are popular phytomedicines for the treatment of gastrointestinal disorders and upper respiratory tract infections. Here we describe a simple and fast capillary zone electrophoresis (CZE) method with ultraviolet detection at 225 nm for the quantification of the major goldenseal constituents, berberine and hydrastine, in herbal remedies containing goldenseal root extracts. Tritoqualine, an antihistaminic drug with a hydrastine-like phthalidisoquinoline structure, was applied as an internal standard. The running buffer was a 1:5 mixture of 500 mM ammonium acetate (adjusted to pH 3.4 with acetic acid) and methanol. Our newly developed CZE method was validated regarding limit of detection (LOD), limit of quantification, linearity, accuracy and precision. For both berberine and hydrastine, the LOD was 1.0 microg/mL and the linearity was obtained between 2.5 and 500 microg/mL. Using our newly developed method, both the alkaloids could be analysed in herbal remedies containing goldenseal root extracts within 8 min.     

Ligand fishing as a tool to screen natural products with anticancer potential

Cancer is the second leading cause of death in the world and its incidence is expected to increase with the aging of the world's population and globalization of risk factors. Natural products and their derivatives have provided a significant number of approved anticancer drugs and the development of robust and selective screening assays for the identification of lead anticancer natural products are essential in the challenge of developing personalized targeted therapies tailored to the genetic and molecular characteristics of tumors. To this end, a ligand fishing assay is a remarkable tool to rapidly and rigorously screen complex matrices, such as plant extracts, for the isolation and identification of specific ligands that bind to relevant pharmacological targets. In this paper, we review the application of ligand fishing with cancer-related targets to screen natural product extracts for the isolation and identification of selective ligands. We provide critical analysis of the system configurations, targets, and key phytochemical classes related to the field of anticancer research. Based on the data collected, ligand fishing emerges as a robust and powerful screening system for the rapid discovery of new anticancer drugs from natural resources. It is currently an underexplored strategy according to its considerable potential.     

Silicon-29 diffusion-ordered NMR spectroscopy (DOSY) as a tool for studying aqueous silicates

The first use of silicon-29 diffusion-ordered NMR spectroscopy (DOSY) is reported, in a study of the speciation of aqueous silicates.     

Donor-donor energy migration (DDEM) as a tool for studying aggregation in lipid phases

A BODIPY-labelled sulfatide (N-(BODIPY-FL-pentanoyl)-galactosylcerebroside-sulfate, hereafter abbreviated as BD-Sulfatide) was solubilised at different concentrations in lipid vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). Time-correlated single photon counting experiments show that the fluorescence relaxation is mono-exponential (with a lifetime of 6.5 ns) at molar ratios of BD-Sulfatide: DOPC that are less than 1:100. The fluorescence steady-state anisotropy decreases monotonously at molar ratios smaller than 1:1000, which is compatible with donor-donor energy migration (DDEM) among the BODIPY groups. A model that assumes DDEM across the lipid bilayers, as well as in their planes, was used to analyse the time-resolved fluorescence anisotropy. Only two parameters appear in the model namely: the bilayer thickness (d) and the average number density (C2) distribution of BD-Sulfatide in the lipid bilayers. The extracted d-values vary between 35 and 40 A, which is about the reported thickness of a bilayer of DOPC (38 A). Hence, the BODIPY groups are preferentially located in the water-lipid interface. At low concentration the experimental C2-values and those independently calculated are in good agreement, while the experimental values gradually become lower with increasing BD-Sulfatide concentration. These results are compatible with an aggregation of the sulfatides and self-quenching of BODIPY, which is clearly established at higher concentrations of the BD-Sulfatide.     

Microcalorimetry as a tool for Cr(VI) toxicity evaluation of human dermal fibroblasts

Occupational exposure to Cr(VI) causes various effects including deep skin ulcerations. Its action mechanisms are not fully understood. In the present study, the evaluation of human dermal fibroblasts heat production was monitored, using microcalorimetry. as part of Cr(VI) toxicity. In control cells, normal heat production was 15±5 pW/cell. Regardless of the Cr(VI) concentration tested (0 to 500 μM), heat production was inhibited over time periods ranging from 3 to 25 h. These results could be correlated with cell mortality and the IC₅₀ for Cr(VI) was 29±4 μM. In the WST-1 bioassay, the IC₅₀ was 35±5 μM (no statistical difference). Thus, Cr(VI) altered the metabolism of the fibroblasts, and led to cellular death. Microcalorimetry can be a useful tool for determining the toxic effect of suspect compounds implicated in the occurrence of pathologies.